A virtual universe (VU) is an interactive simulated environment accessed by multiple users through an online interface. Users inhabit and interact in the VU via avatars, which are a user's representation of himself or herself. These representations can be in the form of a three-dimensional model, a two-dimensional icon, a text construct, a user screen name, etc. Although there are many different types of VUs, there are several features many VUs generally have in common. These features include, for example,                Shared Space: the VU allows many users to participate at once;        Graphical User Interface: the VU depicts space visually, ranging in style from 2D “cartoon” imagery to more immersive 3D environments;        Immediacy: interaction takes place in real time;        Interactivity: the VU allows users to alter, develop, build, or submit customized content;        Persistence: the VU's existence continues regardless of whether individual users are logged in; and        Socialization/Community: the VU allows and encourages the formation of social groups such as teams, guilds, clubs, cliques, housemates, neighborhoods, etc.        
Users may interact with one another in a VU using any number of communication methods. For example, users can communicate with one another via text and/or audio. Audio communications may include playing programmed sounds and/or transmitting a user's voice to other users participating in the VU. However, audio communications do not necessarily transmit user voices that are representative of the user's avatar.